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When attempting to locate trouble a check
of voltages and resistances at the terminal
boards will often indicate the faulty circuit.
Typical
terminal
board
sistances are given in Table 3.
4.
C H ECK I NG
ME N T.
The
following alignment
cribes the tuning and adjustment procedures
of
all circuits of the SSB-1.
complete realignment of
not
be necessary
unless
absolute
need
for it.
such
as
an
IF transformer
only that part of the circuit affected by the
replacement would be realigned.
a. POWER
SUPPLY- Connect
meter between TB-102, terminal 2, and the
chassis.
Set the low voltage power supply
bleeder resistor R-103 to 1500 ohms. Dis
connect the ohmmeter and turn on the RE
CEIVER
switch.
The
ohm resistor,
R-104, should be 17.5 volts
and VR tubes V-104 and V-105 should ignite
within
10 seconds.
R-104 is not 17.5 volts, adjust bleeder re
sistor R-103 for a 17.5 volt reading across
R-104.
b. OSCILLATORS
-
(1) Turn on the POWER and RECEIVER
switches
and
permit the equipment a 15
minute warm -up period.
(2) Insert the RF probe of a V TVM in
T P-203.
A
nominal
should be obtained for the 250 kc oscillator
output.
(3) Insert the RF probe in TP-202.
nominal reading of 9 volts should be obtained
for the
1150
kc
oscillator output.
L-213 for maximum output.
(4) Insert the RF probe in TP-201. A
nominal
reading
of
obtained
for the channel oscillator output
for all four positions of the CHANNEL selec
tor.
(5) Using an accurate frequency stan
dard, which is tuned to 250kc set the 250 kc
oscillator exactly on frequency by adjusting
trimmer capacitor C-272.
1150 kc oscillator with the frequency stan
dard set at 1150 kc.
control C-268
is
the
1150 kc output.
Zero beat with the standard
should occur near the center of the SPEECH
CLARIFIER range.
voltages and
re
A N D
A L IG N
procedure
de
Normally, a
the
SSB-1
would
tests
proved
an
If
a defective part,
is replaced,
an ohm
voltage
across 470
If
the
voltage
across
reading
of
volts
9
A
Adjust
0.35
volts should
be
Also check the
SPEECH CLARIFIER
trimmer across the
c. RECEIVER
(1) Turn
POWER
switches on.
Set RECEIVER GAIN control
fully clockwise.
(2) Insert a V TVM at TP-101 on the
power supply chassis.
Inject a 251 kc unmodulated signal at TP-205,
and tune the primary (bottom) of T-204, and
the primary
(bottom) and
of T-205 for a maximum output.
(3) Retune the signal generator to ap
proximately 235 kc and increase the ampli
tude of the signal generator output.
the signal generator frequency slightly until
a spurious signal is detected as indicated
by
a
reading
on
secondary (top) of T-204 for minimum output
reading.
( 4) Retune the signal generator to 2 51
kc,
and set SPEAKER-HANDSET switch at
HANDSET position.
0.5 volts at TP-101
output should be a maximum of 60 micro
volts.
(5) Check the response of the mechan
ical filter by connecting an oscilloscope at
TP-101 and inserting
Set the oscilloscope level for 20
TP-205.
divisions.
Keeping the input level constant,
vary the input frequency and check the rela
tive output comparing with the chart below.
This check is made with SPEAKER-HANDSET
switch at the HANDSET position.
Input Frequency at
TP-205
250.2 kc
250.3 kc
251.0 kc
253.2 kc
253.4 kc
254.0 kc
{6) Insert a 1401 kc signal at TP-204,
and tune T -203 for
F or a 0.5 volt output at TP-101,
TP-101.
the
signal generator output should
m icrovolts maximum.
(7) Connect signal generator in series
with a 75 ohm resistor to the antenna post
and set
CHANNEL selector
Set signal generator to the channel 1 input
frequency {channel 1 crystal frequency minus
1400 kc).
Adjust the signal generator fre
quency slightly for
cation at TP-101.
30
and
RECEIVER
Use the AC scale.
secondary
(top)
Vary
the
VTVM.
Adjust
For an output level of
the signal generator
a 251
kc signal at
Relative Output at
TP-101
5 divisions
10 divisions
20 divisions
15 divisions
5 divisions
0 divisions
a maximum output at
be 20
to position 1.
maximum output indi
I
I
the
g
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